Gaseous electric discharge device



Aug. 28, 1934..' M. PIRANI I 1,971,939

GASEOUS ELECTRIC DISCHARGE DEVICE Filed Jan. 9, 1930 INVENTOR- Wad/M- Wm ATTORNEY Patented Aug. 28, 1934 a 1,911,939 GASEOUS ELECTRIC DISCHARGE DEVICE M0 Pirani, Berlin-Wilmeradorf, Germany,

assignmto General Electric Company, a corlactation of New York Application January 9, 1930, Serial N. 41906: In Germany February 20, 1929 15 Claims. (Cl. 176-125) The present invention relates generally to gaseous electric discharge devices and more portionlarly the invention relates to means and methods for varying the color of the light emitted from such devices.

It is obvious that for display purposes and indeed for many other purposes a light source which changes the color of its emitted light at determined time intervals is extremely valuable. The object of this invention is to provide a. gaseous electric discharge device which changes the color of its light at determined time intervals.

' The invention attains its object by using ,a gas having a long operating life in such devices in conjunction with a gas having by comparison an extremely short operating life. Rare gases, such as neon, argon and helium, are used as the gas having a long operating life. Common gases, such as hydrogen, nitrogen, and carbon dioxide. are used as the short operating lived gases.

It is well known that all these gases, whether in the-category of the rare gases or the common gases, have their characteristic color radiations when used in electric discharge devices. For example, such a device having neon as its gas content emits a red light. A helium or argon filled device emits a light blue light. Similarly with a nitrogen filled device the light color emitted is yellow, and in the case of carbon dioxide, white. Hence by using an electric discharge device filled with a long lasting rare gas, such as neon, and introducing therein at determined time intervals a suflicient quantity of a quickly used up common gas such as carbon dioxide, the color of the light emitted from said device will change from the color radiations of-the neon, to the color radiations of the carbon dioxide and from that back to the color radiations of the neon when the carbon dioxide is used .up. During the intermediate stages of the light changes the color radiations, therefore, will be those of the mixture of the rare gas and common gas.

In the drawing accompanying and forming part of this specification, practical commercial embodiments of the invention are disclosed, but as such illustrations are primarily for purposes of disclosure, it will be understood that the structures and the operation thereof may be modified in various respects without departure from the broad spirit and scope of the invention.

Fig. 1 is a side elevational view of the gaseous electric discharge device with the gas feeding control circuit shown schematically.

Fig, 2 is a side elevational view of the gaseous electric discharge device with another embodiment of the gas feeding control circuit shown schematically.

Referring to Fig. 1 the device consists of a glass container 1 with electrodes 2, 2 sealed therein. Said container is filled with a rare gashavinga long operating life as neon. Three off-set chambers 13, 13,13 are fused to the container 1, and have rods of gas evolving material 14, 14, 14 mounted therein which are surrounded by heater elements 12, 12, 12. Said rods consist of a sintered mixture of a binding material such as glass and any desired gas evolving material such as lithium hydride, magnesium carbonate or sodium azide. In this embodiment of the invention all three of the aforesaid gas evolving materials are used, 7 one in each of said gas evolving rods 14, 14, 14. The rod containing lithium hydride evolves hydrogen when heated; the rod containing magnesium carbonate evolves carbon dioxide when heated, and similarly the rod containing sodium azide evolves nitrogen when heated. By the use of a suitable heating circuit, such as that shown in the drawing, gas evolving rods 14, 14, 14 may be heated in sequence with a time lag between each heating. The time lag necessary between 0 each heating to obtain a balance between the duration of the rare gas radiations and the common gas radiations is determined by the length of time required for the clean up of the common gas. Having these operating characteristics, the color of the light emitted from the device varies evenly in time from the characteristic color radiations of the rare gas to the characteristic color radiations of each of the common gases in turn. During intermediate stages of color changes the color radiations are those of a mixture of the rare gas with the common gas.

Accordingly the heater circuit consists of an electro-magnet 7-8 having its coil '1 connected in series to one of the electrodes 2, 2 by lead 3 and to secondary 4 of transformer 4, 5 by lead 15. Core 8 of said electro-magnet 7-8 carries a conducting, bridging plate 9 which bridges con tacts 10, 10. Ratchet switch 25 is connected to one of said contacts 10, 10 through thermostatic governor 28. Said ratchet switch 25 has a snap action and is actuated by core 8, on each successive upward movement thereof, to a contact making position with contacts 30, 31, 32 consecutively. Heater elements 12, 12, 12 are connected .to one of the contacts 30, 31, 32 by leads 34, 35,

36, respectively, and to lead 17 by leads 3'7, 38, 39. The usual ballasting device, such as a resistance 40, is connected to one of the primary leads of the transformer- With normal conditions of gas pressure present in discharge chamber 1, that is, with the pressure of the rare gas and the pressure of the common gas, and with consequent normal current density, core 8 carrying bridging plate 9, is in its at rest position, in which position contacts l0, 10, which are connected to primary winding 5' of transformer 4-5 by lead 18, are open and current flows only to electrodes 2, 2. As the common gas cleans up the gas pressure decreases witha consequent increase in current density which causes core 8 to rise due to the heavlercurrent flowing through coil 7.

cuit making position with one oi. the contacts 30, 31, 32. Core 8 continues to rise until plate 9 bridges contacts 10, 10. Current then flows to thermostatic governor 25. After a length of time sufficient to give a balance between the timeof the rare gas radiations and the common gas radiations contact is made in said thermostatic governor 25. Current then flows to one of the heater elements 12, 12, 12, according to the contact 30,

.31, or 32 selected by ratchet switch 25 and common gas is evolved.

If desired, the gas evolving rods 14, 14, 14 may contain the same gas evolving material. This arrangement prolongs the useful operating life of the tube. With this same arrangement of gas evolving rods the ratchet switch may be eliminated and only one gas evolving rod can be connected to the thermostatic governor 28. When this rod is exhausted the next gas evolving rod can be manually connected to the governor 28. It is obvious that this arrangement will also prolong the operating life of the device.

In the embodiment of the invention illustrated by Fig. 2 all three rods 14, 14, 14 are of the same gas evolving material. In this case. however, heater elements 12, 12, 12 are connected in series to the primary winding 5 of the transformer 4, 5 by leads 16. Coil 7 of the electro-magnet 7, 8 is connected to secondary 4 of the transformer 4, 5 by lead 6 and in series with electrode 2 by lead 3. With normal conditions of gas pressure in the discharge chamber, that is, with the pressure of the rare gas and the pressure of the common gas, and with consequent normal current density contacts 10, 10 are open and current flows only to electrodes 2, 2. When the common gas has been cleaned up with a consequent loss of gas-pressure and rise in current density electro-magnet 7, 8 is activated andcore 8 carrying bridging plate 9 is lifted up to bridge contacts 10, 10. Current then fiows to, thermostatic governer 28. After a determined length of time contact is made in the governor and current flows to heater elements 12, 12, 12. The heated common gas evolving rods 14, 14, 14 then evolve gas to restore normal conditions of gas pressure and current density to the tube, in which case core 8 and its attached bridging plate 9. fall back to their atrest position in which position contacts 10, 10 are open. Having these operating characteristicsthe electric discharge device changes the color of its emitted light from the characteristic color radiations of the rare gas, neon in this case, to the characteristic color radiations of the introduced common gas. This change in light color takes place very quickly due to the quick evolution of common gas from the three evenly distributed gas evolving rods. If a gradual change is desired the device may be equipped with a single common gas evolv-'- ing rod in a single oil-set chamber, or the device shown in Fig. 2 may have a slow gas diifusing Ratchet switch25 is moved by rising core 8 until it snaps'into a cir-i material 20, 2o. 20 placed in the neck parts 19, '19,

19 of the off-set chambers 13, 13, 13. The change from the common gas radiations back to the radiations of the rare gas is gradual as the common gas is used up slowly.

While I have shown, described -and pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in p the forms and details of the devices illustrated and in the use and operation thereof may be made by those skilled in the art without departing from the spirit of. the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In gaseous electric discharge devices containing a gaseous atmosphere having agiven excitation characteristic and a long operating life, the method of producing variations in the. color of the emitted light at determined time intervals which consists in introducing therein,'by time delay means controlled bycurrent flowing in said device, a gaseous atmosphere having a different excitation characteristic and a short operating life, whereby the light emitted by said device is that of the short lived gas for a definite period and that of the long lived gas for a like period. r 7

2. An electric discharge device comprising a container, electrodes therefor, a permanent gaseous atmosphere therein, gas evolving material and time delay means in operative relation therewith, said material being adaptable to evolve a diiferent gas at time intervals determined by the time delay means controlled by the current fiowing in said device, whereby the' light emitted by said device is that of the added gas for a definite period and that of the permanent gas for a like period.

3. An electric discharge device comprising a container, electrodes therefor, a permanent gaseous atmosphere therein comprising a rare gas, gas evolving material and time delay means in operative relation therewith, said material being adaptable to evolve a different. gas at time intervals determined by time delay means controlled by current flowing in said device, whereby the light emittedby said device is that of the added gas for a definite period and that of the permanent gas for a like period.

4. In combination, an electric discharge device comprising a container, electrodes therefor, a gaseous atmosphere therein, gas evolving material in operativerelation therewith adaptable to evolve gas at time intervals, 21. thermostatic governor, a ratchet switch and an electro-magnet, said electro-magnet being adaptable on each successive upward movement thereof, to actuate said ratchet switch to contact making positions and to energize said thermostatic governor to close a heating circuit of the gas evolving material.

5. In combination an electric discharge lamp comprising a container, electrodes therefor, a a gaseous atmosphere therein comprising a permanent gas and a short lived gas, gas evolving material in operative relation therewith adaptable to evolve gas replenishments for the short lived gas at desired time intervals, time delay means controlled by current flowing in said lamp to close a heating circuit of the gas evolving material and means to open said circuit. I

6. An electric discharge device comprising a container, electrodes therefor, a permanent gas filling therein having a definite. light radiation characteristic, gas evolving material and time delay means in operative relation therewith, said material being adaptable to evolve gas having a short operating life and a different light radiation characteristic in said device at time intervals determined by the time delay means controlled by current flowing in said device.

7. In gaseous electric discharge devices containing a gaseous atmosphere having a given excitation characteristic and a long operating life, the method of producing variations in the color of the emitted light at determined time intervalswhich consists in introducing therein, by time delay means controlled by current flowing is said device, a gaseous atmosphere having a diflerent excitation characteristic and a short operating life and in such amount that the emitted light is the characteristic radiation of the added gas for a definite period and the characteristic radiation of the long lived gas for a like period.

8. An electric discharge device comprising a container, electrodes therefor, a permanent gaseous atmosphere therein, gas evolving material in operative relation therewith adaptable to evolve a different gas at time intervals determined by time delay means controlled by current flowing in said device and in such amount that the emitted light is the characteristic radiation of the added gas for a definite period and the characteristic radiation of the permanent gas for a like period.

-9. An electric discharge device comprising, a container, electrodes therefor, a permanent gaseous atmosphere therein comprising a rare gas, a common gas evolving material and time delay means in operative relation therewith,

said material being adaptable to evolve a common gas at time intervals determined by the time delay means controlled by current flowing in said device, and in such amount that the emitted light is the characteristic radiation of the'common gas for a definite period and the characteristic radiation of the rare gas for a like period.

10. In combination an electric discharge lamp comprising a container, electrodes therefor, a gaseous atmosphere therein comprising a permanent gas and a short lived gas, gas evolving material in operative relation therewith adaptable to evolve gas replenishments for the short lived gas at such time intervals and in suchamount that the emitted light is the characteristic radiation of the short lived gas, for a definite period and the characteristic radiation of the permanent gas for a like period, time delay means'controlled by current flowing in said device to close a heating circuit of the gas evolving material and means to open said circuit.

11. An electric discharge device comprising a container, electrodes therefor, a permanent gas filling therein having a definite light radiation characteristic, gas evolving material and time delay means in operative relation therewith, said material being adaptable to evolve gas having a short operating life and a different light radiation characteristic in said device at time intervals determined by time delay means controlled by current flowing in said device and in such amount that the emitted light is the characteristic radiation of the added gas for a definite period and the characteristic radiation of the permanent gas for a like period.-

12. In combination, an electric discharge device comprising a container, electrodes therefor,

a permanent gaseous atmosphere therein, gas evolving material in operative relation therewith adaptable to evolve a different gas at time intervals, a thermostatic governor, a ratchet switch and an electro-magnet, said electro-magnet being adaptable on each successive upward .movement thereof, to actuate said ratchet switch to contact making positions and to energize said thermostatic governor to close a heating circuit of the gas evolving material.

13. In combination, an electric discharge device comprising a container, electrodes therefor, a gaseous atmosphere therein, gas evolving material in operative relation therewith adaptable to evolve gas at time intervals, a switch and an electro-magnet comprising a coil and a core, the movements of said core being controlled by current flowing in said device, said core on each successive upward movement thereof actuating said switch to contact making positions, and time delay means controlled by the movements of said core for closing a heating circuit for the gas evolving material after said switch is moved from one contact position to another.

14. In combination, a gaseous electric discharge device comprising a container, electrodes sealed therein, a permanent gaseous atmosphere therein, a plurality of gas evolving bodies in operative relation thereto, each of said bodies evolving a different gas than the other of said bodies and a gas different from the permanent gas in said container, a heater circuit for each of said bodies, a switch comprising a plurality of contacts, each of said heater circuits being connected to one of said switch contacts, an electromagnet comprising a coil and a core, the movements of said core being controlled by current flowing in said device, said core on each successive movement thereof in one direction actuating said switch to contact making positions, and time delay means controlled by the movements of said core for closing the heater circuit selected by said switch.

15. In combination a gaseous electric discharge device comprising a container, electrodes sealed therein, a gaseous atmosphere therein, a gas evolving material in operative relation thereto, a heater circuit for said material, time delay means for closing said heater circuit and an electro-magnet comprising a coil and a core, the movements of said core being controlled by current flowing in said device and controlling,in' turn, said time delay means, the movement of said core in one direction opening said heater circuit.

W FIR-ARI. 

